Figured it out:
- To reverse the move animation, create a new move animation, drag the new light green start point arrow to snap onto the old dark red end point arrow of the first animation, and drag the new dark red endpoint to match the old light green start point. Then set the timing etc to match.
- To reverse the scale animation, set it to scale to a custom % equal to 100 / the old percentage * 100. This does scale from the scaled size. So, to reverse an animation from 100 to 50, that's obviously going to be 200%; to reverse a less simple scaling from, say, 250 to 70 (28%), 100/28*100 = scale by 357%.